Troglitazone is an orally active agent which treats insulin resistance of the thiazolidinedione class, which is currently being investigated in noninsulin-dependent diabetes mellitus (NIDDM) therapy. While the specific mechanism of action is unknown, it has been shown that troglitazone does not act at the pancreas, but rather as a facilitator of increased insulin sensitivity. Data suggests that troglitazone may be effective in decreasing or eliminating the insulin requirement of NIDDM patients taking insulin. In order to further investigate this hypothesis, a 26-week double-blind combination study of troglitazone versus placebo in NIDDM patients requiring insulin has been initiated. The objective of this study is to determine if troglitazone can decrease the insulin requirement in NIDDM patients taking insulin and provide evidence of improved glycemic control. Data from this study will provide information on the proper dosing and management of insulin therapy in NIDDM patients when using troglitazone therapy.